This invention is generally directed towards a method for assembling components on a printed circuit board (PCB) and more specifically addresses a method that permits the efficient utilization of press fit technology and wave soldering. This invention also address a PCB assembly made utilizing this process.
Wave soldering components to a PCB is generally known. Components are assembled onto one surface of the PCB with their leads projecting down through metalized holes to the solder side of the PCB. The PCB is held along its edges by a holding fixture and is carried by a conveyor so that the solder side surface of the PCB engages and passes through a wave of molten solder. It will be apparent that anything disposed on the solder side of the PCB must have sufficient characteristics to withstand the wave soldering operation.
Certain components and assemblies are inherently not suited for wave soldering. One such problem is presented when the PCB is utilized to provide connections with other assemblies on both surfaces of the PCB such as by the use of pins which project from both surfaces. If such pins are inserted prior to wave soldering, the portion of the pin projecting from the solder surface will be soldered. This is undersirable in many applications where connecting reliability is important. Such pins often have a special coating, such as gold plating, to enhance the reliability of connections which would be defeated by a coating of solder. Although it is possible to use a custom shield or cover to prevent solder from engaging the pins, undesirable results often occur. Such a technique usually requires substantial manual operations and results in manufacturing defects.
A PCB known as a backplane can be utilized to interconnect other cards and assemblies. Such backplanes typically have rows of pins which project beyond both surfaces of the PCB allowing the connection of other assemblies or connectors. If components are mounted to the backplane that require soldering, they are typically soldered using a hand held soldering iron after such pins are inserted into the board.
There exists a need for a method which permits a PCB to accommodate interconnection pins which extend from both surfaces while also allowing the use of wave soldering to secure additional components. The present invention addresses this need.